The Canadian Mountain That Feeds Three Oceans

By Ken Jennings -
Oct 14, 2013

Glacier-topped Mount Snow Dome is an 11,000-foot limestone-and-shale summit in the Canadian Rockies. With its four glaciers, the peak is quite picturesque, but to hydrologists—students of Earth’s water—it is more than that. It is unique. Snow Dome is more than 500 miles from the nearest ocean, but the weather at its peak can affect any of three different oceans.

A watershed, as you probably know, is a land area where all the water drains into the same place. Watersheds have boundaries—consider the Continental Divide atop the Rocky Mountains in the western United States. Water on the western slope of the divide flows into the Pacific; water on the eastern slope has a longer trip ahead of it, as it flows into the Atlantic.

Mount Snow Dome is actually a "hydrological apex": It's a single point where three different watersheds meet. To be more specific, its peak is the intersection of the Great Continental Divide and the Arctic Divide. So, for a snowflake drifting down onto Snow Dome, three destinies are possible. If it falls on the western side of the peak, it's headed—eventually—to the Pacific via the Columbia River. A few inches north, and it'll be going to the frigid Arctic Ocean instead. A smidge east, and it'll be routed to the Atlantic via Hudson Bay.

Americans often claim that Triple Divide Peak, in Montana's National Park, is the continent's only three-ocean peak, but that ignores the fact that two of its watersheds empty into the Gulf of Mexico and Hudson Bay—vastly different destinations, yes, but both usually considered to be part of the same ocean, the Atlantic. I have to admit, Canada's divide has the better claim here.

Are there any other three-ocean watershed divides in the world? The Royal Canadian Geographic Society claims there's one in Siberia, but I'm dubious. A USGS map of Siberia shows nearly the entire region draining into the Arctic Ocean. There's no place that I can see where the Atlantic and Pacific Siberian divides meet. (On the south, Siberia drains into no ocean at all, but rather into a huge central Asian basin.) Mount Snow Dome may be one-of-a-kind.